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Anti-Spam Software
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Broadly speaking anti-spam software either filters your email before it is downloaded to your pc (server-side), or after it has been downloaded (client-side). I recommend the latter unless you have a reliable broadband connection, because inspecting the emails which have been filtered out on your mail server can be a slow and unreliable process.
Ideally anti-spam software should allow you to filter emails by two (or more) criteria:
- By message sender
- By message content
Filtering by message sender allows you to set up a "whitelist" of approved email addresses, usually drawn automatically from your address book, a "blacklist" of blocked senders, and a "greylist" of unknown senders. Email senders greylisted can then be added to one or other of the lists as appropriate. On its own, this is not very effective because spammers constantly change their email address, and not all unknown senders are spammers. However the emails which are automatically let through by the whitelist at least enable you to get on with the process of reading emails from known and approved senders.
Filtering by message content is much more complex, but in the long run vital to an effective anti-spam strategy. Combined with sender-filtering it can be a powerful tool. Basically, you train the software how to recognise potential spam by looking for keywords such as "buy", "purchase". "sex" etc. It should always be combined with sender filtering so that messages from known and approved senders do not end up greylisted. It should only filter messages from unknown senders.
Ideally the software should be able to generate two greylists - one for those emails from unknown senders which do not have any of the suspicious keywords, another from unknown senders which contain such keywords. The latter could be called a "dirty-greylist".
Therefore you should be able to inspect your emails in the following order:
- Whitelisted emails., i.e. those from known senders.
- Ordinary Greylisted emails, i.e. those from unknown senders which do not contain any of the keywords you have specified.
- Dirty Greylisted emails, i.e. those from unknown senders which contain the keywords you have specified.
- Blacklisted emails, i.e. those from known spammers - should you ever want to read any of them!
Finally, it is essential to have a reliable method for inspecting your greylisted emails. For this, it is very important that you can view these emails in plain text format. This increases the speed at which you can inspect messages by not wasting time waiting for images and fancy formatting to load. It also aids security because some unwanted email messages can carry nasty scripts which can affect your pc in a manner similar to viruses. Plain text format reading is a useful safeguard in this respect.
All-in-all there is quite a lot of work involved in training anti-spam software to do its work effectively. The time saved through doing this could be well worth the effort and this is a service I can provide.
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